Stain and method of application



STAKN AND METHOD OF APPLICATION Russel ll). Hamilton, Detroit, Mich.,assignor to Chadeloid Corporation, Dayton, Ohio, a corporation ofDelaware No Drawing. Application December 2, 1955 Serial No. 550,783

1 Claim. (Cl. 252-3013) This invention relates to a new and novel woodstain and to a method of producing the same, and is related to copendingapplication Ser. No. 251,999, filed October 18, 1951, now abandoned.

It is an object of this invention to provide a stain of excellentcoloration properties containing a monovalent metal salt of a carboxyalkyl cellulose and a dye which functions to enhance the brilliancy ofthe stain and improve its staining power.

It is a further object to provide a method of incorporating monovalentmetal salt of a carboxy alkyl cellulose into a Wood stain together withbrightening agents.

It is a further object of the invention to provide a process of stainingand a stain that will improve the appearance of the stained wood,particularly in sunlight.

It is a further object to be able to bring out the configuration of thegrain of the wood, to give greater depth to the appearance of thestained wood so that it will have a rich, full bodied and sparklingquality and to further be able to utilize lower grade woods by improvingtheir staining quality and appearance and the definition of their grain.In lower grade woods it is found that the grains are not as distinct andthere is greater monotony as compared with the finer woods in which thegrain stands out and, therefore, presents a handsome appearance whenstained and finished.

It is also an object to place this brightening agent so that it wouldcombine with the other dyes either when it had been put upon the woodand the wood was coated with these dyes to stain it 01 the brighteningagent is put into the dye combination of the stain so that there is onlyone application. In either event the result has been a markedimprovement both in the initial appearance of the wood and in thesubsequent life of the wood after finishing.

Heretofore in the art, the problem has been two-fold in connection withwood stains: first, the aging of the wood finish in sunlight causing itto darken and the wood grain to lose its definition, depth, etc. Thiseliminated the natural contrast between the grain and the rest of thewood and depreciated the appearance of the wood, giving it a uniformdull, dark color. It has also been a problem in finishing Wood not toover-finish it in that the multiple number of treatments such asfilling, staining, sealing, lacquering, rubbing and polishing, whilethey built up at the beginning the life of the wood a handsomeappearance, yet as the Wood aged these multiple coatings also aged andbecame dull, in turn dulling the finishes of the wood.

Derivatives of cellulose of low and medium viscosity such as themonovalent metal salts of carboxy alkyl cellulose, for example, sodiumcarboxy methyl cellulose, have relatively good solubility in water butare substantially insoluble in the organic solvents. Accordingly, thesematerials have not been considered to be useful in conjunction with woodstains where the presence of water is generally undesirable as thissolvent leads to raising of the grain of the Wood. Further, a difficultyencountered with a stain containing carboxy alkyl cellulose has StatesPatent 2,855,369 Patented Oct. 7, 1958 been the relatively deep, dullcolor of the stain produced. The present invention overcomes thisdifliculty and provides a Wood staining composition having improvedcoloring characteristics.

It has been found that the monovalent metal salt of a carboxy alkylcellulose may be effectively employed in producing stains if thecellulose derivative is reacted in solution with an inorganic compoundcapable of yielding a colored ion, the reaction between the inorganiccompound and the carboxy alkyl cellulose effecting a coloredprecipitate. This precipitate is substantially water-insoluble andsoluble in most organic solvents only with the greatest difficulty.However, it has been found that if the precipitated material is treatedwith tetrahydrofurfuryl alcohol containing less than about 1.0% of astrong alkali that solution forms an effective wood stainingcomposition. The solution may be thinned as required with methanol,toluol, or xylol, which are compatible with the precipitate and theresultant material may then be employed as a stain for wood. Theeffectiveness of the resultant staining solution is enhanced whenapplied on woods since the carboxy alkyl cellulose salt has a tendencyto inhibit grain raising.

The optical brightening agents are usually water white and transparentand therefore have not interfered with the Water-soluble aniline dyes oroil-soluble dyes used to stain the wood and they do not discolor thefiller. When used they give the effect with the minimum of finishingoperations of a highly finished piece of wood.

The optical brighteners which have been found useful are the coumarinderivatives, such as beta-methylumbelliferone; the stilbene derivativesand other brighteners that are colorless dyes, fluorescent, directdyestuffs with an atfinity for cellulose. This gives to wood and woodstains an increased surface reflectance and a more brilliant surfacethan an untreated surface. Hydroxy coumarin; 1-naphthylamine-4-sulfonicacid, Na 2-naphthylamine-6, 8-disulfonate; dibenzoylaminostilbenesulfonic acid derivative; naphthalene; benzimidazole, such as2-styrylbenzimidazole orl-(m-acetamido-Z-benzimidazole)-2-(pacetamidophenyl) ethylene; triazinecondensation products; 2,2-ethylenebis (l-benzylbenzimidazole). Forcellulose materials, the following have been found to be useful:o-ethoXy-benzoyl derivatives of 4-,4-diamino-stilbene- 2,2-disulfonicacid, and o-ethoxy-benzoyl derivatives of4,4-diaminostilbene-2,2-disulfonic acid, the disodium sulfonate of4,4'-di (o-ethoxy-benzoyl-amino) stilbene 2,2-'-disulfonic acid beingespecially useful.

I prefer beta-methyl-umbelliferone which is a hydroxymethyl coumarinthat is compatible with the organic solvents used. Styrylbenzimidazoleis also useful as well as 4-methyl-7-diethylamino coumarin.

In some instances the standard beta-methyl-umbelliferones wereprecipitated in stain solutions. In such an event, when placed in theirproper solvent, they can be used to treat the wood before staining. Theyare not used in the stain, filler or finishing coats.

The following are typical examples which we have used for successfulbrightening of Wood and wood stains. We have found that the treatment ofthe Wood first in a suitable solvent emphasizes the grain of the wood.However, the addition to any coat, if soluble in that particular phase,enhances the reflectance and luminescence of the wood in those caseswhere enhancement of the grain effect is not as important. When used inthe top coat with the stains there is a more pronounced elimination ofthe tendency of the woods to yellow and dull under their coatings. Woodsas heretofore treated with wood stains, as they age, tend to yellow anddarken into browns and reds and in the case of blond woods to dull. Wehave found the top coating with the optical brighten ers introduces ablue cast which is not apparent to the eye but negatives this ageing,yellowing and browning effect.

The invention will be more fully understood by reference to thefollowing specific examples, the parts being by weight unless otherwisestated:

Example 1 Two parts by weight of low viscosity sodium carboxy methylcellulose were dissolved in 100 parts by weight of water with rapidagitation and at room temperature (approximately 70 F.). Care wasexercised to avoid lumping of the solute.

A saturated solution of ferric sulfate in water was then prepared byadding an excess of the salt to the water and thoroughly agitating. Asuitable solution may be made using 100 grams water per 25 grams offerric sulfate. The ferric sulfate dissolved very slowly but forms afairly concentrated solution in a short time, which period varies withthe degree of agitation and the fineness of the salt. The solution offerric sulfate was then separated by filtration from the undissolvedexcess of the salt.

The resultant water solution of the carboxy methyl cellulose was thenadded to 40 parts of the saturated ferric sulfate solution slowly andwith constant agitation. A voluminous brown precipitate appeared whichsettled out slowly. This precipitate was then carefully washed withwater and dried. The precipitate has a dark brown and resinousappearance.

Example II A wood staining composition is prepared as follows:

To 100 parts of the dried brown precipitate of Example I there is added100 parts of tetrahydrofurfuryl alcohol containing about 0.5% by weightof sodium hydroxide. The precipitate dissolves slowly in thealcoholalkali solvent, agitation being employed to assist in dissolvingthe precipitate, forming a brown colored staining solution.

To each 100 parts by weight of the resultant brown colored solutionthere is added 50 parts by weight of methanol andv 0.1 part by weight ofbeta-methyl-umbelliferone (7-hydro'xy-4-methyl coumarin).

The stain thus formed may be applied to a wood surface in the mannerknown to the art, giving the wood a vivid uniform brown coloration.

Example III A wood staining solution is prepared as described in ExampleII, except that in place of methanol a 50-50 by volume mixture ofmethanol and toluol is used as the solvent thinner and to which'isintroduced 0.2 part by weight of styrylbenzimidazole as the brighteningagent.

Example IV In this example a staining solution prepared as in Example IIis thinned with toluol or xylol alone employing in this instanceapproximately 40 parts by weight solvent thinner to which is added 0.15part by weight of 4-methyl-7-diethylamino coumarin, and 100 parts byweight of the brown colored staining solution to provide a suitable woodstaining solution.

The use of toluol or xylol as a solvent thinner is generally preferredfor staining close grain hard woods.

Example V A wood staining solution is prepared as described in ExampleII, wherein in place of beta-methyl-umbelliferone there. is substitutedthe disodium salt of 4,4'-di (o-butoxybenzoylamino)stilbene-2,2-disulfonic acid.

It may be noted that other ferric salts having a greater watersolubility may replace ferric sulfate in the above composition.

These water soluble stains so produced are compatible with the opticalbrightener dyes as aforementioned and which are introduced thereto ineffective amounts to produce a blue cast as heretofore pointed out.These dyes are substantially water white and are solvent in the samesolvents as these stains formed from carboxy methyl cellulose.

In each case the initial stain solution has added to it the opticalbrighteners, e. g. styrylbenzimidazole, betamethyl-umbelliferone,amino-naphthalimid, hydroxymethyl coumarin and stilbene, particularlythe derivatives of 4,4'-diaminostilbene-2,2'-disulfonic acid, such asthe alkali metal salt of 4,4'-di (ortho or para aminobenzoylamino)stilbene 2,2-disulfonic acid.

Example VI Three grams of sodium carboxy methyl cellulose are firstdissolved in 100 grams of water as set forth in Example I.

Approximately 20 grams of anhydrous copper sulfate may then be dissolvedin water to form a substantially saturated solution of the salt. Copperdissolves more readily than the ferric salt and accordingly agitationmay be eliminated if desired but is generally preferable to speedformation of the solution. Filtration is not required.

The carboxy methyl cellulose solution may then be added slowly to thesalt solution and a blue precipitate begins to form almost immediately.This precipitate is then washed with water and dried.

To 100 parts by weight of the dried blue precipitate of Example II isthen added parts of tetrahydrofurfuryl alcohol containing approximately1% of sodium hydroxide by weight. The resultant blue solution is thenthinned with methanol as set forth in Example II into which hasbeenintroduced 0.1 part by weight of betamethyl-umbelliferonc.

Example VII A solution containing approximately 2 grams of sodiumcarboxy methyl cellulose is prepared as set forth in Example I.

A green solution, containing 15 grams of anhydrous chromic chloride anda very small amount (0.5 gram) of chromous chloride, as reducing agent,is introduced into grams of water. The presence of the chromous saltassists the solution of the chromic chloride to such extent thatagitation is not required.

The chromic chloride solution is then combined with the solution of thesalt of the cellulose derivative as set forth in Example I to obtain agreenish precipitate which is filtered out and washed with water anddried.

Approximately grams of tetrahydrofurfuryl alcohol containing 0.8% byWeight of sodium hydroxide are then combined with the precipitate (100parts) to form a green stain'which is thinned as described in ExampleII, in thisinstance to each 100 parts by weight of the resultant greensolution there is added 50 parts by weight of methanol and 0.1 part byWeight of the sodium salt of 4,4 di (o amino benzoylamine)stilbene 2,2disulfonic acid.

The above examples are set forth by Way of illustration only sinceinorganic salts which have a fair solubility in water and which insolution yield an ion of a desired color may be reacted with the sodiumcarboxy methyl cellulose to form a complex salt and are considered to bewithin the inventive concept.

It should also be noted that the concentration of alkali used with thetetrahydrofurfuryl alcohol should be kept low as an amount greater thanabout 1% may tend to drive the reaction product of the cellulosederivative and the inorganic salt in the reverse direction.

It will be understood that the brighteners mentioned hereinbefore can beused singularly or in combination with each other.

It will be understood that while there have been given herein certainspecific examples of the practice of this invention, it is not intendedthereby to have this invention limited to or circumscribed by thespecific details of materials, proportions, or conditions hereinspecified, in view of the fact that this invention may be modifiedaccording to individual preference or conditions without necessarilydeparting from the spirit of this disclosure and the scope of theappended claim.

What is claimed is:

A wood staining composition consisting of the reaction product ofchromic chloride and sodium carboxymethyl cellulose dissolved inalkaline tetrahydrofurfuryl alcohol containing 0.8% of sodium hydroxide,and sodium salt of 4,4-di(o-amino-benzoylamine)stilbene-2,2-disulfonicacid.

References Cited in the file of this patent UNITED STATES PATENTS Re.23,703 Ackerman Sept. 1, 1953 2,341,009 Axelrad Feb. 8, 1944 102,654,713 Fleck Oct. 6, 1953 2,691,596 Nack et a1. Oct. 12, 1954

